Low molecular weight heparin

Low molecular weight heparins (LMWH) are obtained from unfractionated heparins and belong to the class of injectable anticoagulants. They differ from standard heparins by their structure and molecular weight. Like their cousins, the LMWH are also used for prevention and for the treatment of venous and arterial thrombo-embolic events (thromboses, pulmonary emboli).

How do the low molecular weight heparins work?

The LMWH have a very similar mechanism of action to the unfractionated heparins. They inhibit two coagulation factors: thrombin and factor X. The way of monitoring and the frequency of injections (one per day compared to at least two per day for the standard heparins) are however different.

Do they have contraindications or precautions?

Like all of the anticoagulants, patients must be monitored because of a risk of bleeding. On the other hand, doctors generally believe that the LMWH are easier to handle than standard heparins as they are administered by subcutaneous injections. They also do not require multiple daily monitoring of the APTT (Activated Partial Thromboplastin Time) as applies to the unfractionated heparins.

Source: Interview with Dr Yannick Béjot, (Dijon University Hospital), 15 June 2011